The solar cell consists of a solar cell module obtained by forming on a single substrate a plurality of solar cells each being a minimum unit for performing photovoltaic power generation. Here, as one of manufacturing steps for a solar cell module, there is a step called “edge deletion.” The manufacturing steps for a solar cell module generally include a step of uniformly forming on a substrate made of a glass or the like thin films including a transparent electrode layer, a photoelectric conversion layer, a back electrode layer, and the like. Here, in the case where thin films are present on a peripheral rim portion (portion having a width from a peripheral rim) of the substrate, a short circuit of the thin films and a metal frame or the like attached to the peripheral rim portion may occur or moisture and the like may infiltrate the peripheral rim portion, resulting in low power generation performance. Therefore, after forming the thin films, edge deletion being a step of removing the thin films present on the peripheral rim portion of the substrate is needed.
For the edge deletion, there is, for example, a method of using sandblasting. In the sandblasting, by spraying powdered abrasives to the thin films on the peripheral rim portion using gas so as to physically remove the thin films. However, in the sandblasting, there are problems in that the powdered abrasives are dispersed also in a power generation region, resulting in low power generation performance, a great amount of dust is generated, and so on. Although other than the sandblasting, there are various methods including directly grinding with a rotating grinder, etching with chemicals, and the like, they have problems in terms of productivity and the like. In view of this, in recent years, edge deletion using a laser beam is considered.
For example, Japanese Patent Application Laid-open No. 2008-66453 (paragraph [0056], FIG. 7B) discloses a method of manufacturing a solar cell module using a laser. In such a manufacturing method, the laser is used to remove, from a transparent conductive layer, a photoelectric conversion layer, and a back electrode layer, which have been sequentially stacked on a translucent substrate, the back electrode layer and the photoelectric conversion layer so that a burr prevention groove is formed. Next, by using a laser to remove the transparent conductive layer, the photoelectric conversion layer, and the back electrode layer in an outside of the burr prevention groove (peripheral region), a peripheral rim isolation groove is formed. At this time, the laser is radiated so that an end portion of a laser beam pattern overlaps with the burr prevention groove and a center portion of the laser beam pattern reaches the outside of the burr prevention groove. By forming the peripheral rim isolation groove in this manner, a short circuit (shunt) between the back electrode layer and the transparent electrode layer, which occurs due to residues of the transparent conductive layer that adhere to the walls of the groove, is prevented from being generated.
However, in the method of manufacturing a solar cell module using a laser, which is described in Japanese Patent Application Laid-open No. 2008-66453(paragraph [0056], FIG. 7B), when the peripheral rim isolation groove is formed, the transparent conductive layer, the photoelectric conversion layer, and the back electrode layer are all removed in the center portion of the laser beam pattern. Here, when the transparent conductive layer, the photoelectric conversion layer, and the back electrode layer are all removed, there is a fear that cracks are generated in a portion of the translucent substrate, which is irradiated with the laser beam, because the laser radiated from the translucent substrate side is reflected by the back electrode layer and heat is accumulated therein. The cracks contribute to a change of the outer appearance of the manufactured solar cell. In addition, the cracks can cause damage and low quality of the solar cell panel, and particularly low power generation performance due to infiltration of moisture and the like over time, and so on.